Secondary battery and electric device

Abstract

A secondary battery and an electric device comprising the secondary battery. The secondary battery comprises: a negative electrode sheet and an electrolyte, where the negative electrode sheet comprises a silicon-carbon composite material and the silicon-carbon composite material has a three-dimensional network crosslinked pore structure; and the electrolyte comprises a carboxylate compound.

What is claimed is: 
     
         1 . A secondary battery, comprising:
 a negative electrode plate comprising a silicon-carbon composite material having a three-dimensional network cross-linked pore structure; and   an electrolyte comprising a carboxylate compound.   
     
     
         2 . The secondary battery according to  claim 1 , wherein:
 a ratio of a mass proportion, EL in g/g, of the carboxylate compound based on the total mass of the electrolyte to a pore volume, Vm in cm 3 /g, of the silicon-carbon composite material is 0.1-11; and   
       
         
           
             
               
                 Vm 
                 = 
                 
                   
                     1 
                     
                       ρ 
                       ⁢ 
                       true 
                     
                   
                     
                   × 
                   
                     α 
                     
                       1 
                       - 
                       α 
                     
                   
                 
               
               , 
             
           
         
          wherein ρ true  represents a true density of the silicon-carbon composite material and α represents a porosity of the silicon-carbon composite material. 
       
     
     
         3 . The secondary battery according to  claim 2 , wherein the porosity a of the silicon-carbon composite material is 2%-30%. 
     
     
         4 . The secondary battery according to  claim 3 , wherein the true density ρ true  of the silicon-carbon composite material is 1.7-2.5 g/cm 3 . 
     
     
         5 . The secondary battery according to  claim 1 , wherein a ratio of a mass proportion, EL in g/g, of the carboxylate compound based on the total mass of the electrolyte to a specific surface area, SSA, of the silicon-carbon composite material is 0.002-0.3. 
     
     
         6 . The secondary battery according to  claim 1 , wherein the specific surface area SSA of the silicon-carbon composite material is 2-10 m 2 /g. 
     
     
         7 . The secondary battery according to  claim 1 , wherein a ratio of a mass proportion, EL in g/g, of the carboxylate compound based on the total mass of the electrolyte to a total pore volume, V1 in cm 3 /g, of pores with a pore size less than or equal to 100 nm in the silicon-carbon composite material is 1-110. 
     
     
         8 . The secondary battery according to  claim 1 , wherein the carboxylate compound is represented by formula I, 
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  each independently comprise at least one of H and halogen-substituted or unsubstituted C 1 -C 6  alkyl. 
       
     
     
         9 . The secondary battery according to  claim 8 , wherein R 1  and R 2  each independently comprise at least one of H, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, trifluoromethyl, difluoromethyl, trifluoroethyl, 2-fluoropropyl, 2,2-difluoropropyl, and 1,1,1-trifluorobutyl. 
     
     
         10 . The secondary battery according to  claim 1 , wherein an electrical conductivity of the electrolyte is 11-19 ms/cm. 
     
     
         11 . The secondary battery according to  claim 1 , wherein a viscosity of the electrolyte is 2.5-3.7 mPa·s. 
     
     
         12 . The secondary battery according to  claim 1 , the carboxylate compound is selected from at least one of methyl formate, methyl acetate, ethyl formate, ethyl acetate, propyl acetate, ethyl propionate, methyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, n-pentyl propionate, isoamyl propionate, ethyl n-butyrate, n-propyl n-butyrate, propyl isobutyrate, n-pentyl n-butyrate, n-pentyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, n-pentyl n-valerate, ethyl 2,2-difluoropropionate, propyl 2,2-difluoropropionate, ethyl 2,2,2-trifluoroacetate, propyl 2,2,2-trifluoroacetate, isopropyl 2,2,2-trifluoroacetate, methyl 2,2,2-trifluoroacetate, and fluoromethyl 2,2,2-trifluoroacetate. 
     
     
         13 . The secondary battery according to  claim 1 , wherein the silicon-carbon composite material comprises: a carbon matrix having a three-dimensional network cross-linked pore structure; and silicon nanoparticles at least partially embedded in the three-dimensional network cross-linked pore structure of the carbon matrix. 
     
     
         14 . The secondary battery according to  claim 13 , wherein a mass proportion of the silicon nanoparticles in the silicon-carbon composite material is greater than or equal to 40%. 
     
     
         15 . The secondary battery according to  claim 13 , wherein the silicon nanoparticles comprise one or more of silicon-oxygen compounds, amorphous silicon, crystalline silicon, and silicon-carbon composites. 
     
     
         16 . The secondary battery according to  claim 13 , wherein the carbon matrix comprises one or more of graphite, mesocarbon microbeads, soft carbon, and hard carbon. 
     
     
         17 . The secondary battery according to  claim 1 , wherein a ratio of a powder compaction density P11 g/cm 3  of the silicon-carbon composite material tested after powder compaction for once under an action force of 20,000 N to a compaction density P21 g/cm 3  of the silicon-carbon composite material tested after powder compaction for twenty times under an action force of 20,000 N satisfies: 1.00<P21/P1≤1.20. 
     
     
         18 . The secondary battery according to  claim 1 , wherein the powder compaction density P11 g/cm 3  of the silicon-carbon composite material tested after powder compaction for once under an action force of 20,000 N satisfies: 1.10≤P11≤1.40. 
     
     
         19 . The secondary battery according to  claim 1 , wherein the secondary battery comprises at least one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery. 
     
     
         20 . An electric device, comprising the secondary battery according to  claim 1 .